Amalgam mixing device



April z5, 1933. E. v. PARKlN 1,905,302

AMALGAM MIXING DEVICE Filed Feb. 2l, 1931 2 Sheets-Sheet l April 25, 1933. E, v. PARKIN AMALGAM MIXING DEVICE Filed Feb. 2l, 1931 2 Sheets-Sheet 2 Patented Apr. 25, 1933 l jf UNITED STATES ERNEST V. PAR-KIN, F TACOMA, WASHINGTON AMALGAM `1vIIxING DEVICE Application filed February 21, 1931K. Serial No. 517,491.

My invention relates to mechanically operated mortar and pestles and has for its particular object the providing of 'such mortar Aand pestles for mixing dental amalgam.

5 The mixing of dental amalgam, composed of dental alloy, a compound of silver, tin, copper', and zinc, and mercury, to form the commonly known silver' dental fillings is difficult because of the peculiar characteristics lo of the metals, especially the mercury, which reacts differently under different pressures and has a tendency to separate into small globules.

I have discovered that the mixing operation must be carried on under a predetermined and uniform pressure to obtain the best results. Mere stirring will not effect the proper amalgamation. In other words, the alloy and mercury must be rubbed with 20 a pressure of approximately fteen pounds fora predetermined period of time of approximately three minutes. The time and pressure elements are important because, to the eye, the intermixture appears complete 25 before the mercury is thoroughly amalgamated with the alloy and it is only by rubbing the amalgam for a predetermined time, under a uniform pressure, that proper amalgamation may be assured.

Heretofore, no mechanical mixing devices have, within my knowledge, been provided capable of producing a satisfactory amalgam; the common practice is to mix the alloy and mercury by hand with the result that 3' there is no uniformity of pressure, all portions of the amalgam are not equally intermixed, and the time element, because of such lack of uniformity in pressure and thoroughness of mixing, becomes impossible to calculate. The average dentist merely mixes the amalgam until it looks all right and then uses it.

An improperly mixed amalgam causes the r filling to be pitted and the edges to break a down and sometimes spheroids or bulges form and in fact a large percentage of all fillings of this character are imperfect for the reasons stated.

Therefore, the main object of my invention is to provide a mechanically operated efficient amalgam-mixing device adapted to thoroughly land uniformly intermix the dental alloy and'mercury under apredetermined pressure, whereby the period of the mixing operation may be approximately determined for producing a substantially perfect amalgam.l v.

I attain .my objects in a mixing device for amalgam comprising a supporting frame, a member eccentrically and rotatably mounted in said frame, a'mortar having a concaved surface mounted under said `supporting frame, a plurality of pestles carried by said member, yielding rubbing ends mounted yon said pestles spring mounted to exert approximately a predetermined constant pressure on the-mortar, means for rotating the member carrying said pestle elements, whereby the said ends travel in eccentric paths on said y mortar and yield respectively. in traveling over said concaved surface.

These and other incidental features of my invention, the 'details of construction and mode of operation are hereinafter fully described with reference to the accompanying drawings.

In the drawings:

Fig. l shows a side elevation of my mixing device; Fig. Q shows a plan view of the same with port-ions broken away to illustrate'the eccentric mounted of the pestle element;

' Fig. 3 shows a section taken on the line 3-3 of Fig. 1 and further illustrates the eccentricity of the pestle element; e

Fig.' Il shows a longitudinal section taken on the line 4 4 of Fig. 2 and illustrates fur- A ther details of construction;

Fig. 5l illustrates an enlarged detail of one ofthe pestle elements; and.

Fig. 6` shows an` enlarged diagrammatic viewof the mortar and illustrates the relative positions and eccentric` movement of th pestle elements. l n

Referring now to the figures, mvV mixing device comprises a circular casing b having legs'b adapted to stand astridea mortar c 1 and support above the mortar and in contact with it a pluralityV of pestles d.

The pestles d are rigidly secured in a cir-y cular member e, in concentric arrangement. The member e is eccentrically journaled in the casing a, as at c', and is provided with an operating crank f or other driving means, not shown, as an electric motor or spring driven means.

TheA surfaceq'q.,oi the mortar c is concaved and the endsof the pestles (l `are provided With caps or rubbing ends la havingrounded ends L, yieldingly mounted kthereon by means of springs z' againstwvhich a flange Z on the ends of the pestles (l bear. Collars 7c are slidably mounted on the pestles l to Which the rubbing ends z, are threaded and serve to prevent the caps from being forced off` the pestles by the force of the said springs z' and also provide'means for adjusting the caps on the pestles d, relatively to the latter.

A.Thus, the -rubbing ends 171, yield to the concaved. surfaceV of the mortar as they are revolved and by constructing the legs b of a predetermined length or supporting the mortar c von a base m of predetermined height, the pressureof the rubbing ends 71, on the surface of the mortar can be regulated to a nicety to providethe requisite approximate fifteen pounds pressure of each pestle element. f

In operation, yassuming the dental alloy and mercury to have been placed in the mortar and the latter to have been adjusted so that each' pestle end bears on the mortar with equal'pressure, the crank f is then operated, which revolves the pestles eccentrically about the mortar, see Fig.` 6, in circular paths, which overlap, as shown `by the broken lines and cover everyportion of the mortar surface. The ends h are heldfagainst individual rotation by set-screws p sliding in slots d in the pestlesd so that they rubthe alloy and mercury against the surface of the mortar and at the same time yield as they travel over the concave-surface, to bear with substantially equal pressure on all points of the mortar surface, and thoroughly intermix the alloy and mercury.

Thus, the supporting frame a and therewith the pestles cl may be conveniently placed over the mortar and it Will be assured that the ends 71, Will each time bear With the proper and equal pressureupo-n the mortar, since such pressure fvvill be determined by the relative lengths of the legs b and the heightof the base m. Further, every particle of the amalgam Will be thoroughly and equally operated upon and the mixing period may be accurately determined, which, as I have discovered, is approximately three minutes under a given pressure. Y

.I claim:

- l. In a'mixing device, a mortar having a concaved Working face, a straddle frame adapted to be mounted over said mortar, an eccentric pestle element mounted in' said frame for rotation about the axis Vof the mortar, said pestle element comprising a group of individual, non-rotating, longitudinally yielding spring controlled members of such length as to bear on the concave surface'of said mortar With a predetermined pressure.

2. In a mixing device, a mortar having a concaved working face, a straddleeframe adapted to be mounted over said mortar, an eccentric pestle element mounted in said frame for rotation about the axis of the mortar, said pestle element comprising a group of individual, non-rotating, longitudinally yielding spring controlled members of such length as to bear on the concave surface of said mortar with a predetermined pressure, means for adjusting said mortar relatively to said pestle, therebyY to vary the pressure of the said pestle members thereon.

ERNEST V. PARKIN. 

